If successful, Fiat bosses are said to be planning to close GM’s Vauxhall plants based at Ellesmere, which employs 2,700 staff, and Luton, which employs 2,000 people.

The plans emerged following a meeting between Fiat chief executive Sergio Marchionne and Klaus Franz, the labour leader of Opel, GM’s German arm.

Fiat is expected to cut 18,000 jobs across Europe if it successfully acquires GM, with plants also expected to close in Germany and Italy. The factory closures are said to be planned for between 2011 and 2016.

A spokesman for Fiat said: “It is not information generated by Fiat and does not form part of any plan prepared by Fiat.”